Development of a Bacterial Biosensor is proposed to ensure that platelets are sufficiently free of bacteria to be safely transfused into patients. Preliminary results with one prototype demonstrated that rRNA from Helicobacter pylori, a model bacterial pathogen for humans, could be detected by hybridization sandwich assay within two minutes and at 10/4 cells sensitivity. A second prototype with a long-period with along- period Bragg grating, which does not require a sandwich assay or signal fluorophore, showed that human IgG could be identified even in a crude bacterial lysate. Both prototypes work with either nucleic acids or proteins, can function as point-of-care devices, and are faster than commercially available tests. Each prototype will be modified and then tested two ways: first, by hybridization with a universal rRNA probe to detect bacterial contamination of platelets. Second, with receptor and/or antibody to detect extracellular release of soluble vascular endothelial growth factor (sVEGF) from platelets when bacteria are present. Each of the four possible configurations will be optimized and compared for sensitivity, specificity, ease of cooperation, potential cost, and other factors. The resulting instrument should prove a powerful and effective tool for rapid and direct determination of platelet safety and for other health related applications. PROPOSED COMMERCIAL APPLICATIONS: The risk of receiving bacterially contaminated platelets may be 50 to 250 times higher than the combined risk per unit of transfusion-related viral infection with HIV-1/2, HCV, HBV, and HTLV-I/II. About four million units of platelets are transfused globally every year. Medicare already adds a $35 premium to each unit of viral-cleansed blood product. By extrapolation, therefore, a minimal cost of $5 per unit to certify platelets as sufficiently free of bacteria would create an estimated $20 million market and would save 100 to 150 lives every year just in the United States alone.